Rotor blade for a wind power plant

ABSTRACT

The invention concerns a rotor blade of a wind power installation and a wind power installation. One advantage of the present invention is to provide a rotor blade having a rotor blade profile, and a wind power installation, which has better efficiency than hitherto. A rotor blade of a wind power installation, wherein the rotor blade has a thickness reserve approximately in the range of between 15% and 40%, preferably in the range of between about 23% and 28%, and wherein the greatest profile thickness is between about 20% and 45%, preferably between about 32% and 36%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 11/846,391, filed Aug. 28, 2007, and U.S. patentapplication Ser. No. 11/846,396, filed Aug. 28, 2007, each of which is adivisional application of U.S. patent application Ser. No. 10/516,804,filed Aug. 4, 2005, issued on Apr. 15, 2008 as U.S. Pat. No. 7,357,624,which is a national stage application filed under 35 U.S.C. §371 ofInternational Application No. PCT/EP03/05605, accorded an InternationalFiling Date of May 28, 2003, which claims priority to German ApplicationNo. 102 25 136.3, filed Jun. 5, 2002 and German Application No. 103 07682.4, filed Feb. 21, 2003. These applications are hereby incorporatedherein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention concerns a rotor blade of a wind power installation, and awind power installation. As state of the art in this respect attentionshould be directed generally to the book ‘Windkraftanlagen’, Erich Hau,1996. That book contains some examples of wind power installations,rotor blades of such wind power installations as well as cross-sectionsof such rotor blades from the state of the art. Page 102, FIG. 5.34,illustrates the geometrical profile parameters of aerodynamic profilesin accordance with NACA. It is to be seen in that respect that the rotorblade is described by a profile depth which corresponds to the length ofthe chord, a greatest camber (or camber ratio) as the maximum rise of amedian line over the chord, a camber reserve, that is to say thelocation with respect to the profile depth where the greatest camber isprovided within the cross-section of the rotor blade, a greatest profilethickness as the largest diameter of an inscribed circle with the centerpoint on the median line and the thickness reserve, that is to say thelocation with respect to the profile depth where the cross-section ofthe rotor blade assumes its greatest profile thickness. In addition theleading-edge radius and the profile co-ordinates of the underside andthe top side are brought into consideration to describe thecross-section of the rotor blade. The nomenclature known from the ErichHau book is to be retained inter alia for the further description of thecross-section of a rotor for the present application.

2. Description of the Related Art

Rotor blades are to be optimized in regard to a large number of aspects.On the one hand they should be quiet while on the other hand they shouldalso afford a maximum dynamic power so that, even with a quite slightwind, the wind power installation begins to run and the nominal windspeed, that is to say the speed at which the nominal power of the windpower installation is also reached for the first time, is alreadyreached at wind strengths which are as low as possible.

If then the wind speed rises further, nowadays when consideringpitch-regulated wind power installations the rotor blade is increasinglyset into the wind so that the nominal power is still maintained, but theoperative surface area of the rotor blade in relation to the winddecreases in order thereby to protect the entire wind power installationor parts thereof from mechanical damage. It is crucial however thatgreat significance is attributed to the aerodynamic properties of therotor blade profiles of the rotor blade of a wind power installation.

BRIEF SUMMARY OF THE INVENTION

One advantage of the present invention is to provide a rotor bladehaving a rotor blade profile and a wind power installation, whichinvolve better efficiency than hitherto. The advantage may be attainedby a rotor blade having a rotor blade profile with the features as setforth in at least some of the disclosed embodiments. Other advantageousdevelopments are described herein.

The specific co-ordinates of a rotor blade profile according to theinvention are set forth in a Table 1.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention is illustrated hereinafter by a number of drawings inwhich:

FIG. 1 shows a perspective view from the front of a wind powerinstallation according to the invention,

FIG. 2 shows a perspective view of a wind power installation accordingto the invention from the rear and the side,

FIG. 3 shows a view of a wind power installation according to theinvention from the side,

FIGS. 4-8 show views of a rotor blade according to the invention fromvarious directions,

FIG. 9 shows a view on an enlarged scale of a wind power installationaccording to the invention,

FIG. 10 shows a view of a rotor blade according to the invention,

FIGS. 11-17 and 19 show various views of a wind power installationaccording to the invention, and

FIG. 18 shows a cross-section of a rotor blade according to theinvention (in the region near the hub).

DETAILED DESCRIPTION OF THE INVENTION

FIG. 18 shows the rotor blade profile described in accordance with oneillustrated embodiment. In particular, in the region of the rotor bladewhich adjoins the rotor blade connection, (for connection to the hub)the profile is of a selected size and shape. The profile described inthe present embodiment is provided in the first third of the rotor blade1, with respect to the overall length of the rotor blade 1. In thisrespect the overall length L of a rotor blade 1 may definitely be in therange of between 10 m and 70 m, depending on the nominal power which awind power installation is to involve. Thus, for example, the nominalpower of a wind power installation from the corporation Enercon of typeE-112 (diameter about 112 m) is 4.5 MW while the nominal power of a windpower installation from Enercon of type E-30 is 300 KW.

What is particularly characteristic in terms of the profile of the rotorblade 1 according to the invention is that the greatest profilethickness is between about 25% and 40%, preferably between 32% and 36%,of the length of a rotor blade chord 9. In FIG. 18, the greatest profilethickness is about 34.6% of the length of the rotor blade chord 9. Thechord 9 extends from the center 2 of the rotor blade trailing edge 3 tothe foremost point 4 of the rotor blade leading edge 5. The thicknessreserve TR, that is to say the location in relation to the blade lengthwhere the greatest profile thickness occurs, is between about 20% and30% of the length of the chord, preferably between 23% and 28%, andabout 25.9% in the illustrated example. The greatest thickness isascertained perpendicularly to the chord 9 and the reserve TR is relatedto the rotor blade leading edge.

In addition, FIG. 18 shows mean camber line 7. The camber line 7 resultsfrom half the respective thickness of the rotor blade 1 at a point.Accordingly, the camber line 7 does not extend in a straight line, butinstead extends between oppositely disposed points on anincreased-pressure side 10 of the rotor blade 1 and a reduced-pressureside 11 of the rotor blade 1. The camber line 7 intersects the chord 9at the trailing edge 3 of the rotor blade 1 and the leading edge 5 ofthe rotor blade 1.

The camber reserve CR in the cross-section of a rotor blade 1 is locatedbetween about 55% and 70% of the length of the chord 9, and preferablybetween about 59% and 63%. In the illustrated example the camber reserveCR is located at about 61.9% of the length of the chord 9. The amount ofcamber C at the camber reserve CR can be between about 4% and 8% of thelength of the chord, and preferably between about 5% and 7% of thelength of the chord. In the illustrated example, the camber “C” is about5.87% of the length of the chord.

It is further particularly striking in terms of the profile of the rotorblade 1 that the reduced-pressure side 11 of the rotor blade 1 ‘cuts’the chord twice at points 12 and 13. That is to say in that thereduced-pressure side 11 of the profile is of a concave configuration,while in the front region of the profile, the increased-pressure side 10is of a convex configuration. In the region where the increased-pressureside 10 is of a convex configuration, in the corresponding, oppositelydisposed region on the reduced-pressure side 11, this region 14 isdelimited by an almost straight line.

While it might be previously known for the reduced-pressure side 11 tobe provided with a concave curvature or for the increased-pressure side11 to be provided with a straight-line boundary as individualcomponents, the combination of having one opposite the other is a newfeature according to invention. In particular, the combination of thosetwo measures is significant in the profile of the rotor blade 1according to the invention and is characteristic in respect of the rotorblade profile according to the invention.

The rotor blade trailing edge 3 of the illustrated profile is alsonoticeably thick. This thickness, however, does not cause any problem inregard to the creation of sound at the trailing edge 3 of the rotorblade 1 because the illustrated profile is in the inner third of therotor circle and there the orbital speed is not very high.

One embodiment of the x-y-coordinates of the profile is shown in FIG. 18and is reproduced in Table 1. The profile of the rotor blade 1 can bemade substantially as described herein. Of course, variations from Table1 are possible and the invention can still be obtained; use of the exactx-y values in Table 1 is not required.

As shown in FIG. 1, to improve the aerodynamic shape of the rotor blade,it is of such a configuration, in the general region of the rotor bladeroot 15, that there it is of its greatest width W and thus the rotorblade 1 is of a trapezoidal shape (in plan) which is more or lessapproximated to the optimum aerodynamic shape. Preferably in the regionof the rotor blade root 15, the rotor blade 1 is of such a configurationthat the edge 16 of the rotor blade root 15, which is towards a pod 18of a wind power installation (FIG. 15), is adapted to the externalcontour of the pod cladding 19 of the pod 18 in at least one angularposition, for example it is adapted in such a way that a very smallspacing S, for example a spacing S of between about 5 mm and 100 mm,exists between the pod cladding 19 and the edge 16 of the rotor bladeroot 15 which is towards the wind power installation and the externalcontour of the pod cladding 19 when the rotor blade 1 is positioned inthe nominal wind position.

A rotor blade 1 with the above-indicated properties affords asignificantly higher increase in power of about up to 10%. By virtue ofthat increase in power, a wind power installation operating at a windspeed below the nominal wind speed, can achieve a higher power output.In addition, the wind power installation reaches its nominal poweroutput earlier than hitherto. Accordingly, the rotor blades 1 can alsobe rotated to a pitched position, which can reduce sound emission andthe mechanical loading on the installation.

In that respect the invention is based on the realization that the rotorblade shape which is common nowadays is investigated in a wind tunneladmittedly using different wind speeds but with an air flow which isalways uniform. In nature, it is rare that the wind blows uniformly, butrather the wind is subject to a stochastic law. Standard rotor bladeprofiles, as a consequence of gusts, involve detachment of the flowprecisely in the inner region of the blade near the rotor hub 17 wherethe blade no longer has an aerodynamically clean and optimumconfiguration. This flow detachment phenomena is propagated a distancealong the rotor blade 1 in the direction towards the rotor blade tip. Asa result, the flow can become detached from the rotor blade 1 in abubble-shaped region and thus result in corresponding power losses. Inthe case of the present invention and in regard to the above-describedsituation, it is possible to achieve a considerable increase in poweroutput by virtue of a rotor blade 1 which is of a clean configuration inthe inner region of the rotor blade according to the embodiments of thepresent invention.

If now a known standard profile were to be used instead of theempirically ascertained blade profile, which is described herein, then,to afford an aerodynamically clean configuration for the rotor blade,approximately double the profile depth relative to the length of thechord of the rotor blade could be required in the region of the rotorblade near the hub 17. The profile thickness in the front region permitsthe transmission of air loads and permits the rotor blade to attain alift value C_(A) greater than 2.

As is known from the state of the art, rotor blades are usuallyconstructed to entail a saving of material to the greatest possibleextent in the inner region. Typical examples in that respect aredisclosed in the state of the art, which has already been referred toabove, in ‘Windkraftanlagen’, Erich Hau, 1996, on pages 114 and 115. Itcan be seen therein that the greatest profile depth is always attainedat a certain distance from the rotor blade connection, that is to say inthe region near the rotor blade connection, in which respect material issaved in those rotor blades in accordance with the state of the art. If,however, a shape approximating a trapezoidal shape is used, then thegreatest width of a rotor blade is not at a spacing relative to therotor blade connection but precisely in the region of the rotor bladeconnection itself. That structure then therefore does not save thegreatest possible amount of material in the inner region of the rotorblades.

The approach to saving in material, as described above, has beendeveloped by considering the static manner of the flow conditions inregard to calculating/developing the rotor blades 1. In addition,current calculation programs for rotor blades divide the rotor blade 1into individual portions and calculate each rotor blade portion initself in order to derive an evaluation for the overall rotor blade.

As noted above, wind does not blow uniformly and statically over a givensurface area region, but markedly exhibits a stochastic behavior. Thelow peripheral speed of the rotor blade 1 in the inner region near therotor hub 19 influences the wind speed and may cause the angle ofincidence to change in that region in response to and dependant on theinstantaneous wind speed. As a consequence, detachment of the flow fromthe rotor blade 1 can frequently occur in the inner region of the rotorblade 1.

A hysteresis effect is operative in such a situation. When the previouswind speed occurs again, that is to say after a gust is past, the flowis not the same at the rotor blade 1 again. Rather, the wind speedfirstly has to fall further (the angle of incidence must therefore befurther changed) until the air again bears against the surface of therotor blade 1. If, however, the wind speed does not decrease, it maycertainly happen that, for a prolonged period of time, in spite of theafflux flow of the wind to the rotor blade 1, a relevant force isexerted on the rotor blade 1 because the flow has not yet come to bearagainst (i.e., flow cleanly over) the rotor blade surface again.

The risk of flow detachment can be reduced by the embodiments of therotor blade described herein. For example, the detachment risk isreduced by the relatively thick profile. The thick profile of rotorblade 1 provides an increase in power can also be well explained byvirtue of due to the hysteresis effect, once flow detachment hasoccurred, the power losses are maintained over a considerable period oftime for rotor blades in accordance with the state of the art.

A further part of the increase in power can be explained by virtue ofthe fact that the wind follows the path of least resistance. Thus, ifthe rotor blade is very thin in the inner region near the hub 17 becauseof saving material, then this can be viewed as a ‘slip hole’ in theharvesting area of the rotor circle (i.e., around and proximate to thepod 18), through which air preferentially flows. In this case, it ispossible to see that the common calculation programs based on uniformdistribution over the rotor circle area may not be sufficientlyaccurate.

In one embodiment as best illustrated in FIGS. 3 and 11, the ‘slip hole’can be ‘closed’ by virtue of the trapezoidal configuration of the rotorblade 1 in the region near the hub 17, then an improved distribution ofair flow over the entire circular surface area can be achieved. Inaddition, the efficiency of the outer region of the rotor blade is alsoincreased somewhat. Accordingly, ‘closing’ the ‘slip hole’ makes acontribution to the higher power output of the rotor blade 1.

Another insufficiency of the current calculation programs is that theyconsider the rotor blade portion directly adjoining the ‘slip hole’ as afull-value rotor blade portion which it cannot be, because of theparticular flow conditions, which results in frequent flow breakdowns.

FIGS. 3 and 11 show a wind power installation according to oneillustrated embodiment. The three rotor blades 1 have an almost seamlesstransition with respect to the external configuration of the podcladding 21 and with respect to the hub cladding 19 when the rotorblades 1 are in a nominal wind position. FIG. 9 illustrates that if thewind increases above nominal wind speed, then the rotor blades 1 aremoved slowly to change their pitch to the wind by pitch control or pitchregulation and a large spacing “S” develops between the lower edge 16 ofthe rotor blade 1 and the hub cladding 19 and pod cladding 21,respectively. FIG. 11, however, shows that when the contour of the hubcladding 19 and the contour of the pod cladding 21 substantiallycorrespond to the edge profile of the rotor blade 1 in the region nearthe hub 19 and which, when the rotor blade 1 is set in an angle ofincidence at the nominal speed, is directly below the rotor blade sothat there is only a small gap “S” between the structure and the rotorblade in the region near the hub.

When the rotor blade 1 is in the feathered position, with reducedsurface area towards the wind, the rotor blade 1 is parallel to thelower edge 16 that is towards the pod 18 and the spacing between thelower edge 16 and the external contour of the pod cladding 21 is at aminimum, preferably being less than 50 cm or even less than 20 cm.

When the rotor blade 1 is set into the wind, it involves a large surfacearea even in the very near region of the rotor blade (the slip hole isvery small). The above-mentioned reference Erich Hau shows that therotor blade in the state of the art decreases regularly in the regionnear the hub 17 (the rotor blades are there less wide than at theirwidest location). Conversely, the widest location of the rotor blade 1according to at least one embodiment of the invention is in the regionnear the hub 17 so that the wind can be utilized to the best possibleextent.

Referring back to the rotor blade profile shown in FIG. 18, the leadingedge radius 5 is approximately 0.146 of the profile depth.

The reduced-pressure side 10 has a longer, almost straight region. Inthis region, at between 38% and 100% of the profile depth, the radius isabout 1.19 times the length of the profile depth. Between 40% and 85% ofthe profile depth, the radius is about 2.44 times the profile depth.And, between 42% and 45% of the profile depth, the radius is about 5.56times of the profile depth.

In the region between 36% and 100% of the profile depth, the maximumdeviation from an ideal straight line is about 0.012 of the profilelength. This value is an important variable as the curvature radiusvaries and the greatest curvature radius is already specified in therespective regions.

In the illustrated embodiment of FIG. 18, the length of thereduced-pressure side 10 is about 1.124 of the length of the profiledepth while the length of the increased-pressure side 11 is 1.112 of thelength of the profile depth. This means that the reduced-pressure side10 is only immaterially longer than the increased-pressure side 11. Itis advantageous if the ratio of the reduced-pressure side 10 length tothe increased-pressure side 11 length is less than 1.2, preferably lessthan 1.1 or in a range of values of between 1 and 1.03.

It can be seen from the illustrated Figures that the rotor blade 1 hasits greatest profile depth directly at the spinner or hub 17, that is tosay at the outside of the pod 18 of the wind power installation. For awind power installation with a rotor diameter of 30 m, the profile depthat the spinner 17 is between about 1.8 to 1.9, preferably 1.84. If thenthe spinner 17 is approximately of a diameter of 3.2 mm, the ratio ofthe profile depth of the rotor blade 1 at the spinner to the spinnerdiameter is about 0.575. It is further advantageous if the ratio of theprofile depth to the spinner diameter is greater than a value of 0.4 orin a range of values of about 0.4 to 1. In the above-specified example,the ratio of the profile depth to the rotor diameter is about 0.061. The‘slip hole’ can be made as small as possible if the ratio of the profiledepth to the rotor diameter is greater than a value of between 0.05 and0.01.

In another example, a rotor blade 1 with a profile cross-section similarto the one shown in FIG. 18, the first third of the profile, has aprofile depth at the spinner of about 4.35 mm, a spinner diameter of 5.4m and a rotor diameter of about 71 m. Thus, the value of the profiledepth to the spinner diameter is 0.806 and the ratio of the profiledepth to the rotor diameter is again 0.061. The above-indicated valuesrelate to a triple-blade rotor with pitch regulation.

As described, a rotor blade 1 according to another embodiment of theinvention can have its greatest profile depth in the region near the hub17 and the rotor blade 1 can further include the rotor blade portion 30.FIG. 15 illustrates the rotor blade portion 30, which is a physicallyseparable component with respect to the rotor blade 1, but is consideredto a functional part of the rotor blade 1 with respect to carrying airloads. The rotor blade portion 30, although not an integral part of therotatable rotor blade 1, can be an integral, constituent part of the hubcladding 19 or affixed to the hub cladding 19 of the hub 17, which isfurther a part of the pod 18, in a variety of ways (e.g., joined,screwed and so forth). In addition the lower edge of the rotor bladeportion 30, that is to say the edge which faces towards the pod of thewind power installation, can be substantially adapted to or matched tothe external contour of the hub cladding 19 and/or pod cladding 21 inthe longitudinal direction. Accordingly in this case, when a rotor blade1 is in the feathered position, (practically no longerwhere hardly anysurface area which faces towards the wind), the rotor blade 1 isparallel to the lower edge 16 that is towards the pod 18 and the spacingbetween the lower edge 16 and the external contour of the pod is at aminimum, preferably being less than 50 cm or even better less than 20cm.

As is known, it is precisely when dealing with very large rotor blades 1that a very great rotor blade width is involved in the region near thehub 17. In order for such rotor blades 1 to be transported, the rotorblade 1 can be of a two-part configuration, in which the two parts areseparated during transport and re-assembled after transport. In such anembodiment, the two parts are connected together before being installedon the wind power installation, for example by way of screw connectionsand/or secure connections (e.g., adhesive). Large rotor blades may beaccessible from the interior for being fitted together so that such arotor blade can have of a unitary assembled appearance on the exteriorand the separation lines are scarcely visible or not visible at all.

As initial measurements show, the rotor blade 1 according to embodimentsof the present invention can markedly have an increased efficiency incomparison with previous rotor blades.

As can be seen from FIGS. 4-8, the rotor blades 1 have their greatestprofile depth in the region near the hub 17. In addition, the rotorblade portions, along their respective edge profiles, are configured tosubstantially conform to the contour of the hub cladding 19 and/or thepod cladding 21. Accordingly, at least for the position in which therotor blade 1 assumes an angle that corresponds to wind speeds up to thenominal wind range, there may be a very small spacing relative to thepod cladding 21.

FIG. 16 illustrates a seamless transition between the feathering portionof the rotor blade 1 and the non-feathering portion 30 is indicated inby the lack of any demarcation line between the blade portions 1 and 30.

The rotor blade portion 30, which as previously stated, is not anintegral constituent part of the overall rotor blade 1 is affixed to thepod 18, or more specifically to the hub cladding 19 of the hub 17. Therotor blade portion 30 located on the outside of the pod is fixedthereto and arranged at an angle corresponding to the angular positionof a rotor blade 1 up to the nominal wind speed. Thus, at wind speeds upto the nominal wind, there are minimal gaps between the lower edge 16 ofthe rotor blade 1, the rotor blade portion 30, and the pod 18,respectively. The rotor blade portion 30 can be screwed to the pod 18 orcan also be glued or joined in one piece to the pod 18.

FIG. 19 illustrates that there is only a quite small ‘slip hole’ for thewind that cannot be seen from a distance by virtue of the configurationof the rotor blades 1 in relation to the rotor blade portion 30.

FIG. 18 shows a cross-section through a rotor blade according to theinvention as taken along line A-A in FIG. 17, that is to say the profileof the rotor blade in the region near the hub.

FIG. 17 also includes an indication of what is to be understood by thediameter D of the spinner.

The rotor diameter is described by the diameter of the circular areawhich is covered by the rotor when it rotates.

As can be seen from FIG. 15 and other Figures the rotor blade portion 30of the rotor blade 1 which is not an integral constituent part of therotatable rotor blade 1 is an integral constituent part of the outsidecladding 19 of at least the hub 17. The respective portion 30 can bescrewed to the pod or can also be glued or joined in one piece to thepod.

Referring back to FIG. 11, a wind and/or weather sensor 31 is attachedto the pod 18 according to one illustrated embodiment. The sensor 31 canmeasure a variety of parameters such as wind velocity, direction,temperature, etc. This information may be recorded or transmitted.

TABLE 1 X-Y-COORDINATES x y 1.000000 0.013442 0.983794 0.020294 0.9583570.030412 0.930883 0.040357 0.899462 0.050865 0.863452 0.062358 0.8238900.074531 0.781816 0.086987 0.737837 0.099513 0.692331 0.111993 0.6453630.124434 0.597614 0.136709 0.549483 0.148731 0.503007 0.160228 0.4810360.170758 0.425769 0.179639 0.397598 0.186588 0.374996 0.191889 0.3561860.195840 0.339750 0.198668 0.324740 0.200524 0.310542 0.201512 0.2967310.201704 0.232999 0.201174 0.269154 0.200007 0.255115 0.198267 0.2408760.195985 0.226479 0.193185 0.212006 0.189892 0.197571 0.186146 0.1833150.181995 0.169384 0.177505 0.155924 0.172745 0.143051 0.167780 0.1308500.162675 0.119369 0.157478 0.108625 0.152229 0.098610 0.146953 0.0892970.141664 0.080653 0.136362 0.072636 0.131036 0.065201 0.125679 0.0583120.120269 0.051931 0.114786 0.046015 0.109229 0.040531 0.103598 0.0354570.097893 0.030772 0.092113 0.026461 0.086252 0.022520 0.080332 0.0189370.074321 0.015688 0.068240 0.012771 0.062095 0.010196 0.055378 0.0079260.049601 0.005911 0.043298 0.004164 0.036989 0.002755 0.030661 0.0017090.024300 0.000953 0.017915 0.000415 0.011534 0.000088 0.005186 0.0000000.000000 0.000197 −0.007376 0.000703 −0.013612 0.001550 −0.0198160.002704 −0.025999 0.004080 −0.032162 0.005649 −0.038281 0.007477−0.044316 0.009639 −0.050245 0.012124 −0.056078 0.014883 −0.0618290.017905 −0.067491 0.021204 −0.073045 0.024779 −0.078485 0.028618−0.083809 0.032721 −0.089004 0.037087 −0.094062 0.041711 −0.0989730.046594 −0.103723 0.051740 −0.108301 0.057150 −0.112695 0.062824−0.116897 0.068769 −0.120893 0.074991 −0.124669 0.081500 −0.1282190.088310 −0.131521 0.095450 −0.134551 0.102955 −0.137294 0.110872−0.139735 0.119262 −0.141872 0.128192 −0.143724 0.137734 −0.1453160.147962 −0.146667 0.158934 −0.147800 0.170663 −0.148727 0.183106−0.149431 0.196155 −0.149877 0.209657 −0.150001 0.223475 −0.1497150.237539 −0.148932 0.251855 −0.147579 0.266497 −0.145597 0.281578−0.142949 0.297206 −0.139628 0.313400 −0.135651 0.330088 −0.1310160.347173 −0.125692 0.364627 −0.119588 0.382602 −0.112537 0.401480−0.104293 0.421912 −0.094548 0.444568 −0.083182 0.468376 −0.071217 0491608 −0.060017 0 514034 −0.049898 0.535806 −0.040854 0.557225−0.032760 0.578580 −0.025495 0.600131 −0.018956 0 622095 −0.0130590.644620 −0.007755 0.667811 −0.003015 0.691690 0.001179 0.7161040.004827 0.740707 0.007908 0.364985 0.010392 0.788448 0.012236 0.8108170.013425 0.832004 0.013957 0.852100 0.013834 0.871284 0.013058 0.8897970.011606 0.907926 0.009441 0 925997 0.006502 0.944381 0.002701 0.963552−0.002134 0.984409 −0.008335 1.000000 −0.013442 0.000197 −0.0073760.000703 −0.013612 0.001550 −0.019816 0.002704 −0.025999 0.004080−0.032162 0.005649 −0.038281 0.007477 −0.044316 0.009639 −0.0502450.012124 −0.056078 0.014883 −0.061829 0.017905 −0.067491 0.021204−0.073045 0.024779 −0.078485 0.028618 −0.083809 0.032721 −0.0890040.037087 −0.094062

All of the above U.S. patents, U.S. patent application publications,U.S. patent applications, foreign patents, foreign patent applicationsand non-patent publications referred to in this specification and/orlisted in the Application Data Sheet, are incorporated herein byreference, in their entirety.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

1. A wind power installation rotor blade, comprising: a rotor bladetrailing edge and a rotor blade leading edge; a rotor blade chord thatextends from the center of the rotor blade trailing edge to a foremostpoint of the rotor blade leading edge; and a cross section positioned ina lower third section of the rotor blade located adjacent to a rotorblade connection, the cross section having a thickness reservepositioned in the range of 23% to 28% of the length of the rotor bladechord and a greatest profile thickness in the range of 32% to 36% of thelength of the rotor blade chord.